What Does Venous Occlusion Plethysmography Measure?
Venous occlusion plethysmography measures total forearm blood flow, of which, under resting conditions, blood flow through skeletal muscle is the bulk (50% to 70% of total), the remainder being flow through skin. [7,8] The hands must be excluded from the circulation, as blood flow in the hand is predominantly through skin, and there is a high proportion of arteriovenous shunts; hand blood flow has different pharmacology and physiology from forearm blood flow. [1,9,10]. The underlying principle of venous occlusion plethysmography is straightforward: If venous return from the arm is obstructed and arterial inflow continues unimpeded, the forearm swells at a rate proportional to the rate of arterial inflow. [10]. In practice, excluding the hands from the circulation is achieved by inflating a wrist cuff to suprasystolic pressures. Arrest of forearm venous return is usually achieved by inflating a cuff placed around the upper arm to 40 mm Hg for 10 seconds, a maneuver that does not affect
